Obese women more likely to get breast cancer: Study shows post-menopause women are prone to greater incidence and mortality risk of breast cancer, if they are obese.

Obesity is a growing health problem, particularly prevalent among first world countries. Although not a disease it is dangerous nonetheless as it has been linked to many other diseases such as diabetes and heart disease.

According to CDC, some 78.6 million people are obese in the US, which makes roughly one third of the total adult population.

According to a new study, obese women had a higher chance of developing breast cancer post menopause. Compared to women with normal weight, obese women were found to have up to 58% higher risk for breast cancer.

Research Data: Risk Of Breast Cancer

According to the American Institute of Cancer Research, one in eight women in the United States will develop breast cancer. Approximately 40,700 lives will be lost to breast cancer this year alone. AICR also estimated that 33% of breast cancers could be preventable if we take care of our diet and control our weight by exercising.

The study was a secondary analysis of data gathered from the Women’s Health Initiative clinical trials in the year 1993-1998 which enrolled 67,000 women. The clinical trials were designed to test the effects of various factors such as diet modification, calcium, vitamin D supplements and hormone therapy on fractures, cancer and heart disease.

Follow-up data of more than 13 years showed that 3388 breast cancers were detected by 2010. The risk of invasive breast cancer was among the highest in obese women.
The researchers grouped women on the basis of their Body Mass index (BMI), which is measure of the ratio of weight to height. A normal BMI value is considered to be below 25, whereas a BMI of over 35 is considered severely obese.

Lead author of the paper Marion L. Neuhouser of the Fred Hutchison Cancer Research Center in Seattle WA, explained the possible link of obesity and breast cancer, “Obesity increase estrogen in postmenopausal woman because estrogen is produced by fat tissue. Fat tissue is also responsible for secreting inflammatory factors as well as insulin resistance. All of the these may increase risk of breast cancer.”

What was surprising in the study was that women who had normal weight at the start but put on weight after menopause also had a greater risk, an astonishing increase of 36% percent. But losing weight after menopause did not lower the risk.

The study also found that women who are very obese are 86% more at risk for hormone driven cancers such estrogen receptor (ER+) and progesterone receptor (PR+). Also these women were more likely to have larger tumors and increased risk of mortality.

“We are unable to change our family history or our genes but we can change our lifestyle habits. We need to aim to maintain a healthy weight to lower breast cancer risk.” Neuhouser added.

Co-author of the accompanying journal editorial, Dr. Clifford Hudis commented, “Obesity is a growing concern in many ways, including the contribution it makes to cancer. We need to prioritize scientific and public policy decision making to help limit the health burden it brings.” The study was published online in JAMA Oncology.